A technique commonly used in the manufacture of composites starts from a preform formed by several fabric layers comprising reinforcement fibers (carbon fibers, glass fibers, etc.). These fabrics or layers which are placed on a forming mold gradually bond to one another by means of a binder which is applied at determined points, and then the mold is closed, which will provide the preform with the end shape by means of applying heat and pressure during a determined time period.
The different fabric layers are of flexible fabrics with patterns with a two-dimensional geometry, i.e., they have the shape and size suitable for the composite part to be obtained. In industrial practice, the two-dimensional fabric layers are typically placed manually on the mold because it is necessary to correctly place them and gradually fix them to one another.
If this process is to be automated, a manipulator which grasps the different two-dimensional fabric layers or patterns and takes them to the forming mold can be used, but once there, the manipulator has to let them fall onto the mold so good placement of the layers cannot be assured, especially when the mold has a complex geometry.
Manipulators which allow grasping and transporting flexible elements by means of vacuum suction cups or similar elements are known today, but they all have the problem that they cannot assure good placement of the fabrics in the mold or automatically apply adhesive between the different fabric layers. Thus, patent application US2010007065A1 describes a gripping device containing a frame in which a device configured to grasp and maintain at least one carbon fiber fabric is included. This frame further contains another device for draping the carbon fiber fabric on the mold. On the other hand, patent application US2008080962A1 describes another similar device for transporting limp objects such as carbon fiber fabrics or the like, comprising a surface by means of which the fabric is grasped. This surface is made up of different elements which will or will not begin operating, depending on the shape and dimensions of the fabric to be grasped. Although these devices allow grasping carbon fiber fabrics with different shapes and placing them on a mold, this is only possible provided that the shape of the mold is simple. The holding elements do not have relative movement with respect to one another, therefore the fabric will be draped on the mold by releasing it thereon, therefore not being able to assure that the fabric will adapt well to the shape of the mold. Likewise, the article by Tarsha Kordi, M. et al. (Department of Mechanism Theory and Machine Dynamics (IGM) of the TWTH University of Aachen, Germany—http://www.igm.rwth-aachen.de/): “Development of a Multifunctional Robot End-Effector System for Automated Manufacture of Textile Preforms”, published in the conferences “Advanced intelligent mechatronics, 2007 IEEE/ASME”, ISBN: 978-1-4244-1263-1, pages 1-6 (2007) describes a gripping device comprising a support structure in which are articulated respective pantographic type side racks and suction, cold or needle gripping element carriers, which allows grasping a fabric in a two-dimensional plane and placing it on a three-dimensional mold. Some of the gripping elements are assembled on arms which can pivot with respect to the support structure, and thus bend the textile preform at its ends, forming an angle with the central part of the textile preform. Also in this case, the adaptation of the fabric to the mold is only possible for simple three-dimensional shapes.